Mold construction



May 24, 1938. H, E. MCWANE 2,118,764

MOLD CONSTRUCTION Filed OC'lZ. l5, 1934 Inu m e H64 j /4 ,476.67 2329525 23 soy Patented May 24, 1938 mma-.rf ortica MOLD CONSTRUCTION Henry McWane, Lynchburg, Va.

Application October 13, 1934, Serial I*Io.-.748,229.A

3 Claims..

This: invention relates to casting; and `more particularly. has reference .to a mold and a -.core for Vuse in connection therewith.

Considerable `diilculty. vhas beenexperienced in thef'cpast. when it hasV been necessary to'usesa core in. casting objects in -metal or other mate rials.. During shrinkage ofthe casting upon cool* ingr` there is of course a .tendency to displace the.

cores If; this tendency is. resisted by a xation of thecore, appreciable `stresses and strains are set up. in `the. casting, frequently resulting. in f the splitting or crackingthereof; In. order to overcome. thisit has .been proposedto employ cores that arecapable of moving upon shrinkage of the casting.

Certain disadvantages have .inhered in .such priorY cores, however, inasmuch as they have usually been of the destructible type suchas sand cores, for instance, and furthermore it has heretofore been necessary to manually arrange the core in the mold cavity prior to each pouring operation..

Oneof the objects of my inventionis tov over-Y come the above mentioned difliculties.

Another object of my inventionis 'to provide a permanentY core which is free to moveuponv shrinkage of the castingand whichis automati.

cally repcsitionedfor a pouring operation upon removal of the casting fromthe mold cavity.

Withthese and otheri objects in view which:

may be incident to my improvements, the invention consists in the parts andvcombinationsto be hereinafter set forth and claimed, with thek understanding that the several necessary velements comprising my inventionmay loe-varied inconstruction, :proportions and arrangement without departing from the spirit and scope of the appended claims.

In order to make my .invention more clearly` understood,.I have shown in the accompanying drawing means for carrying the same into practical eii'ect without limiting theimprovementsin their fuseful'applications to the particular conh` structionswhich; for the purposeof explanation, have been made the subject of illustration.l

In fthe. drawing:

Figure: l isa top plan rview of a mold section equipped with my invention.

Figure 2 is a sectional .view along the line. 2-.-2

.t of Figure. I ,showing one type of core that may i viewof the core shown4 Figure 5 `is a sectionallview alongthe line `5-'-5 of Figure2, vlooking in the direction of the arrows.r

Figure 6 is a view partly insectionand-partly. in elevation "of a coresimilar to the core -of Fig-` ure'=2,'savefonly1that it isv cylindrical insteadof frusto-conical.

Figure 7 isa view partly in section and partly* in elevation kof a somewhat modified type 'of core and associated mechanism.

Figure 8 is a sectional View along .the line 8 3 of Figure' 7; looking in the direction of the ar' rows.

In the drawing, I have shown my Yinvention as. applied to `a mold for casting plates 4in whichiit` is desired to provide apertures, but'it`wil1'iof course -be appreciated that it is of `wider application,.and may be used'in connection with'cast.- ings'of various types.

In Figure 1 I have'shownthe lower half of :at mold 1| `provided with the usual mold'cavities 1 and gates 3. The cores forming the subject mat'- terr ofmy invention I have designated generallyv by the numeral 4." The metal in the cavities 2 isadapted to flow about the cores 4 to thereby formxbolt:` holes or other apertures in'the iin.` ished casting.. If guide grooves are. desired* inthe apertures -oi the casting, a Vrib 5 'may be formed `upon the core.

Thecore may be `of frusto-conical shapepas-l indicated atti inFigure 2, orv may be cylindrical,

as vshown at l in Figure 6. Of course, cores of.' various other shapes may be employed.

As shown inrFigures 2 .rand 6, the core isv mounted on a stemt which extends'finto achan` nel 5l drilled in the mold and runs from the base thereof to thev mold cavity.

As best shown in Figures 4 and 5, I prefer thatf the stem 8 Yand the-channel 9 be 'triangular 'in cross section, andthat Vthey becorresponding triangles.` The positionof thev core in the mold cavity is such thatfthe stem 8 fits tightly withinJ the apex of the channel, as shownlin Figure '4.i This serves to .seatthe core and to insure a seat-x ing ofthe core atfone place for all pouring-'operations.

The fstem may be secured in the channel 9 in' variousways; and I have merely showntwo waysv of mounting the stem therein. v

In Figures 2 through' I have shown a pivotal.J arrangement.A In these figures thelower portion"v of the channel 9 from the dotted :line fl I" ter-' minates in a square channel l2. In .this channel I have provided a pivot bar I3 suitably supported.. by. arms.A i4 A horizo-ntalslot l5 is cutLintoxthe apex of the stem 8 adjacent its lower end, and

is adapted to receive the pivot bar I3. It will therefore be appreciated that the stem 8 and the core 4 are adapted to swing about the bar I3 as a pivot. The arc described by the core 4 is very slight and only an inappreciable clearance between the core and mold cavity need be maintained. This clearance is not suiiicient to permit of the leakage of any of the molten metal that is poured into the cavity.

To facilitate the assembly of the core in the mold, I prefer to drill a recess IB in the base of the mold and adjacent and communicating with the channels 9 and I2. This recess may be provided with shoulders I1, if desired. A block I8 is adapted to be inserted in the recess to form the base and one wall of the channel I2. Screws I9, or other suitable fastening means, may be employed to secure the block in position.

It will be noted that the block I 8 lls the recess I6, but in the top wall of the recess there is formed a channel 2I which communicates with channel 9. In the channel 2l there is positioned a coil spring 22 which is adapted to have one end bear against an end wall of the channel 2| and its opposite end bear against the base of the triangle of stem 8. This spring serves to maintain the apex of stem 8 against the apex of channel 9, but of course resiliently permitting movement of the stem 8 from this position. As stated above, I prefer that the stem 8 and channel 9 be triangular in cross section, in order to guide the stem to its seat for a pouring operation. It will of course be appreciated, however, that under some circumstances the shape of the stem and channel may be varied.

As stated above, the movement of the core in Figure 2 is, to all intents and purposes, horizontal. However, in Figures '7 and 8, I have shown a modied arrangement in which the core and its associated elements truly slide horizontally rather than being pivoted. In this form the stern 8 and channel 9 may be triangular, as in the case of the previously described core structure, or may be of a different shape, as above mentioned. Secured to the base of the stem 8, preferably by means of a screw 23, is a block 24. The block 24 is preferably triangular, and is adapted to slide within a correspondingly triangular recess 25. The recess 25 is drilled from the base of the mold and is adapted to be filled by a plug 26. The plug 26 is maintained in position by means of screws 21 or other appropriate fastening means, It will of course be appreciated that that part of the recess 25 filled by the plug 26 need not be triangular, and furthermore, the block 24 need not be triangular. I prefer, however, that the plug 24 and recess 25 should be triangular in order that the block and core might be guided to a uniform seat for the pouring operation.

Communicating with the recess 25 is a channel 28 adapted to hold a coil spring 29. One end of the coil spring bears against the base of channel 28 and the other end against the base of the triangular block 24. It will therefore be appreciated that the spring 29 tends to urge the block 24 into the apex of the triangle of recess 25 and to maintain it in that position. At the same time, however, it permits of retraction of the block 24 from that position. It will also be noted that the base of the core S lies flush upon the base of the mold cavity, and that the block 24 ts snugly between the upper part of recess 25 and the top of block 26.

From the foregoing, the operation of my device is believed to be apparent. In the case of the form shown in Figure 2, the shaft 8 is extended into channel 9, and the slot I5 fitted over the pivot bar I3. The spring 22 is then arranged between the stem 8 and the end Wall of channel 2I.

In the case of the device shown in Figures 7 and 8, the stem is inserted in channel 9 from the mold cavity, and the block 24 is then screwed thereon, after first arranging spring 29 in its channel 28. 'I'he block 26 is then screwed into position.

It will be noted that during a casting operation the core 4 is adapted to freely move with respect to the core body and in the direction of shrinkage v of the casting. As is well known, a casting shrinks so that its edges recede from the walls of the mold cavity, and the channels 9 are so formed as to take care of this direction of movement by the core 4. With respect to the device of Figure 2, while it is true that the core theoretically describes an arc, in actual practice this arc is so slight that for all intents and purposes the movement is in a single plane. As pointed out above, a slight clearance suffices to take care of the throw of the arc, a clearance which is not sufcient to permit a leakage of the molten metal.

When the casting is removed from the mold cavity, the springs 22 and 29 urge the stem 8 and core 4 to their seated position for the next pouring operation. The triangular shape of the stem and block 24 determines the uniform seated position for all pouring operations.

The advantages of my invention are believed to be obvious. It permits of the free contraction or shrinkage of a casting upon cooling, thus preventing the imposition of objectionable stresses and strains in the casting. Also, upon removal of the casting, the core is automatically returned from its displaced position to its true seat, a seat which is uniform for every casting. It is also obvious that my invention is inexpensive to manufacture and effects an appreciable economy over those prior structures in which the core has been manually seated in the mold cavity.

While I have shown and described the preferred embodiment of my invention, I wish it to be understood that I do not confine myself to the precise details of construction herein set forth, by way of illustration, as it is apparent that many changes and variations may be made therein, by those skilled in theart, without departing from the spirit of the invention, or exceeding the scope of the appended claims.

I claim:

l. In a casting apparatus, a mold having a cavity, a permanent core located in the cavity, said core being provided with a stem pivoted to the mold, and means for resiliently maintaining the core at a predetermined position in the cavity.

2. In a casting apparatus, a mold having a cavity, a core mounted upon a stem, the said stem lying within a channel extending from the mold cavity and pivoted therein, and means for resiliently maintaining the stern in a predetermined position.

3. In a casting apparatus, a mold having a cavity, a triangular shaped channel extending from the cavity, a core adapted to close the cavity end of said channel, a stem of triangular shape secured to the core and pivoted within the channel, and resilient means to urge the stem into one apex ofthe channel.

HENRY E. MCWANE. 

